Sense Sonnet - Chiller

"P" as in Paste

Ammonia is a bleach, and so
Used on your teeth would whiten up,
As many folks want, doncha know!
Ancient Romans would use a cup
Of ammonia, from which to brush,
To make their teeth all white and clean.
But ammonia from where? - hush, hush.
'Twas a secret kept 'twixt and 'tween.
Perhaps the toothpaste you now use
Contains the secret, Romans knew.
Ingredient list to peruse
Could contain a chemical clue.

So with your choppers, you just might
Brush your teeth till urine the white.